Pump for delivering hot, corrosive media

Abstract

A pump for delivering hot, corrosive material having a shaft seal comprising a seal gap through which hot gases flow, and wherein the sealing gases also flow around the pump bearings for the purpose of cooling the bearings.

We claim: 
     
       1. Pump for delivering hot corrosive media, comprising a drive section, a pump body, and a drive shaft which is sealed off from the medium to be delivered by a shaft seal, wherein a) the shaft seal consists of a stator ring separating the pump body and the drive section and through which the drive shaft passes while leaving a seal gap between said drive shaft and said stator ring, and wherein   b) the pump body, the stator ring and all portions of the pump body which contact the media to be pumped, are manufactured from a material which is resistant to corrosion and high temperatures, and wherein   c) one or more dry-running bearings are arranged in the drive section to mount the drive shaft and further comprising   d) a gas flow channel in the drive section, having a gas supply inlet and a gas discharge, and which communicates with the dry-running bearings and seal gap so as to enable gas supplied to the inlet to flow around the dry running bearings, and a portion of said gas to then enter the seal gap in the drive section and flow through said seal gap into the pump body, while the remainder of the gas leaves the drive section through the gas discharge.   
     
     
       2. Pump according to claim 1, wherein a magnetic coupling is provided in the drive section to transmit rotational movement to the drive shaft. 
     
     
       3. Pump according to 1, wherein the dry-running bearing is a ceramic rolling contact bearing. 
     
     
       4. Pump according to claim 1, wherein the dry-running bearing has coatings on the running surfaces to reduce the coefficient of sliding friction. 
     
     
       5. Pump according to claim 1, further comprising a conventional axial ring seal between the stator ring and the drive section. 
     
     
       6. A method for pumping a corrosive material which comprises pumping said material with a pump according to claim 1, wherein a hot gas is supplied to the gas supply inlet of said pump at a pressure sufficient to maintain the pressure in the gas flow channel of said pump at a pressure which is higher than the pressure of the corrosive material in the pump body of said pump. 
     
     
       7. Method according to claim 6, wherein the temperature of the hot gas is above 120° C. and the pressure of the hot gas in the gas flow channel is above 1.5 bar. 
     
     
       8. Method according to claim 6, wherein said hot gas is superheated steam.